Annoyance following noise exposure can be considered to convey a "possible loss of fitness signal" (PLOF-signal) indicating, that the individuum's Darwinian fitness decrease if she or he continues to stay in that situation. Especially, non-familiar conspecifics appearing in the habitat diminish fitness of the inhabitants because they are going to use the same but restricted ressources. Therefore, sounds carrying the information that they are men made are likely to evoke more annoyance than other sounds of equal level and spectral density.
In an experiment, subjects were exposed to recorded sounds of ocean surf and party murmur. Both sounds were carefully equalized regarding spectral energy and overall level (Leq(A) =52 dB). In the "man made" sound condition, subjects felt significantly more annoyed and were significantly more impaired in a free recall memory test. However, physiological stress indices (potassium/sodium measured in saliva) didn't discriminate significantly between the conditions. The results support the hypothesis, that, considered biologically, the main function of noise annoyance is to warn a person that fitness may diminsh, but not to induce actual stress. This explains the frequentlly reported finding that noise, though annoying, causes only little or even no physiological stress reactions.
Referat in der Gruppe Verkehrspsychologie, Mittwoch, 31. März 1999, 11:30, HS 21
